Telegraph system



Patented Julyl 10, 1945 2,379,910 TELEGRAPH SYSTEM Fullerton S; KinkeatL, deceasedglatefof New York,

N. `Yaby Rita` Smith Kinkead, administratrix,` Trudeau,.-N. Y.,fassignor` to.Bell.Telephone.Lah

` v `orat'ories, Incorporated poraticnj'of New York `nppiiafitinniotmlier;19, 19.42;;.seria1 Nol V462,5'17

siemens (cuirs-69') This invention relates to` `teleg-raipl'i transmission systemsand more particular-ly toi telegraph l systems adaptedJ to Work over inferior transmission lineshaving high electrostatic capacityfand 10W Aleakage resistance. i

` VMore particularly this-invention relates tol im-` proVements'in-the telegraph transmissionsystems l disclosed inl United i States Patents ltr-311,870

granted toCramer, October- 4,1938', and Gramer et al. 2,143,000,-granted January 10, 1939,` which quiremenr tirannie, relay fait@ respond: to surges t transmitted over the17k line is?eliminated!` l Hence the receiving conditions applied to the'irelay alone may be employed to ofthe relay. In addition,pfurther improvement' is secured )by connecting*` af pair etfoppositelylpoled` noni-linear deter-mine the `a'dijustments circuit elements orcoppereoxid'e-rectierslaround y or 'inshunt with the line winding ofthe relay. The constants of these rectiiier'el'ernenits. are so l0 ypatents are herelcyfrnadea part of this-specica` related"tothewinding` of` thevrelay towhichlthey tion-aait fully included' herein; i arelconnected.andthe.currentsandipotentialsofy In thesystems disclosed in theabove-identied the-vsystern tliatlduring thelrecepti'on of` signals v patents, the biasA or distortiolmofitelegraphA sigy and during steady stateconditions, these elements nais transmittedy over telegraph linesf is substanf 15 passa little `or no current.. However,` lWhen-sig-` tially independent of andunaffeetedby'theleaknais. are `transn'iitted from this endl' of: the-line, ageresistanceor changesin the leakage-resistance thefrectierswill'by-passalargaportioirvof the of the transmission path, As explained in these surge: -currents'vwhiohcharge andidischargeA the patents, the compensation` for changes inthe linewcapacity; l n l leakage resistance ofthe line: is obtained by prop# 20 l `A'tithe opposite Aendl 0fE the. line, Where* ground erly choosing the transmitting potentialsandthe isl connected to` the transmission conductor dirt-- bias supplied tothe receiving relay` ing-the transmissionoffmarkingpulses andwhere Whilethesystemsdisclosed in the above-'ii'enti` a spacing potential of oppositeipolarity towthje iied patents are operative over long telegraph lines 1 marking potential atthe distant orl rstlend and subject-tolconsiderable variation andi leakage re*- 25 twice? its value or magrltlld `S`2JDD1edlOlle-lih sistanea and overlines havingl-almoderateamount during.- tranSmiSsiOn `0f Spacing pulses; the rey of line capacity, it has-been'discoveredltnatthese quirem'entthatf-threeivine relays failtofrspond i systemsfdo -notf operate particularly, well* over t'cnc'harging` surgeslilias been removedbyiprovidlineshaving high electrostatic capacity; l in'g-` an auxiliary repeating relayioperated under Inaccordance withthe'present'inventionpthe 130 controlof thefrnain"I receivinglrelay-y liavingfa l circuits'arerearranged solthattlieylwill operate@ special-biasing or lockinglwindinglwhich prevents satisfactorily over:` high capacity lines and `atti-le the. repeating' relayfrfro-xn-l following' `tl1`efs-hc5r't same time prevent the` leakageresistancea off the momentary operationsinthe inainreceivingf-relay linesfromfadding toorichanglng the distortionof dminglthetransmission:ofisignals from thisffe'nd the signals transmitted over the` line.` ,35 of the-lineduetothe surgefcurrents-Whichcharge In' accordance With the` present invention, i and:dischargethel-cable capacity. i transmitting potentialsiare applied tolthe ends:` of In addition special networks areI providedl for the transmission conductor inL accordancevv-ith` varying the bias of the receiving relays-linaccordthe disclosures of the alcove-identitledv patents. ance'iwith the character ofthe-signalsreceived by j *Hon/ever, the circuits-are rearranged So that? the` 40 tlie'serfelays. Networks ofthisftype'areldescribed l effects ofthe high capacityof thetransmission" invg-reater det'ailinthe copendinglafpplication of path are greatlyreduced orfeliminatedi KinkeawSerialNo; 462,'57Bfled1'10n0ctl I9"J 1942,

At theend `of the system at which positive' and nDW-"Patent`iNo.1 2,860,878, granted Oct: 124i V1942i'. negative potentialsV of equal magnitudesu are l` 'Ilhlforegoinglobjects andi features of` tiiis'in'; applied'tothe signallconductorin'accordancefwith 45 ventionl aswell as:` other objects and features the signals to loe` transmitted, the receiving-relay thereomayl hemore readilyfunde'rstod frorntlie circuit is-arranged-scthat it`Y Will follovvthe sigf-` following desoriptio'n'- when read? with 'reference nals transmitted byj the equipment? a-t this' end to the attachedrdrawing which `showsv a typical of the line and atthesame tiinerepeatthe sig'- er'nb'odiment o'ilthednvention.: As is -iwellunder'- nals received by the station: Tliis-isacoornplished 50 stood';v the l claimsE appended heretoispecically by rearranging the-circuitj ofA therloiasing winding v pointlout novel ffatures oflthisinventioii riclare` of thsrelayso that current through' itis-reversed notilimited.I to the "specific embodirne' when-spacing"impulses are transmittedfrom this" inventiondisclosedand dscribedindetai endof the-line. By causing-this i'elffiwiz-o"respond` Thelgllre ofthe `drawingl showslawtypicallm to signalstransrnitted* inboth directions; the re- ,i

sediment @f1 thissinventibn asapplied tetwoiing As is understood by those skilled in the art,"

both the leakage resistance 26 and the capacity 2,5 may be concentrated at one or more points along the line, but in the usual line. and circuit both of these quantities ywill bel'distributed more or less uniformly along a considerable. portion of the line or transmission path.

As understood by those skilled in the art, the line 24 may comprise any suitable low frequency telegraph transmission path -including both open wire lines and cable circuits as well as the socalled telegraph transmission paths of any of the simplexed or compositedtelephone and telegraph lines` or systems.` I

,gThe, outlying station Ais provided with a selector or receiving magnet It and a suitable receiving instrument which in a preferred embodiment of this invention will comprise a printing, instrument such as described in greater detail in United States Patent 1,745,633, granted to S. Morton et al. onK February 4, 1930, and 1,904,164, granted to S. Morton et al. on April ,1.8,v 1933. Both of these patents are hereby made apart of this application as .if fully included herein.

. Station A is also provided with transmitting contacts, I I which are controlled either by means of a keyboard, key or other suitable type of transmitting instrument in accordance with the signals'it is desired to transmit from station A. The operationof the contacts II is repeated by .both relays I3,and I4 which follow these signals andv cause them to be repeated over line 24. Relays I3 land I4 areshown in their marking positions, in which positions they cause a negative potential, from rectifier I2 to be applied to line 24.; -When contacts open, relays I3 and I4 are operated to the position opposite to the position` shown in the drawing at which time they apply positivepotential from rectifier I2 to line 24. A single rectifier is employed at station A Aasthe source of power consequently the pulses of positive and negative current transmitted over the line or the magnitude oi the potential applied to the line at this station during both of said conditions will be substantially; the same.

The pulses of current transmitted from relays Hand I3 flow through the upper winding of the receiving ,relay 2| and to the repeater station B at the' distant end of the line. The receiving relay 2| is also provided Witha lower or` biasing winding, a circuit of which extends from ground Y lthrough the lower Winding of relay 2| and thence to ground through theshunting resistancel, I5 and I6. The circuit of `the biasing winding of relay 2| also extends from ground through the lowerwinding of this relay and resistance I9 to thearmature of transmitting relay I4. Hence vlwhen the polarity of the potential applied to `-Resistances |5`and I6 andcondenser I 'I are ,employed to vary the bias of relay 2| in accordance with the signals received from this line,

as set forth in detail in the above-identified copending Kinkead application.

A network comprising a condenser and resistance 20 is connected between the m-ain line and the circuit of the biasing winding. This network tends to cause the surges transmitted 'to and received from the transmission conductor 24 to flow substantially equally through both the upper and lower windings of relay 2| in opposite directions Vand thus greatly reduce the `eilect of the surge current upon the operation of this relay.

In order to further reduce the effects of the line surges due to charging and discharging of the'line capacity, the rectier elements 22 and 23 are connected in the reverse direction around the main line winding of relay 2|. The values of these rectiers are so chosen that during normal' operation of the system and' during idle periodsthey pass a very small portion of the current flowing through the upper winding of relay 2|. However, during transmission from station A, the charge'and discharge of the line capacity 25 causes the voltage across the upper winding of relay 2| `to raise and this in' turn causesthe impedance of one or the other of the unilateral conducting devices 22 or 23 to'decrease so it will pass aconsiderable portion of this charging or discharging current and thus prevent it from af- -fecting the operation of the receiving relayA at stationA.l For amore detailed description of the operation of non-linear circuit elements as applied to telegraph systems and relays, reference is made to United States Patent 2,147,690, granted to Cramer et al.v February 21, 1939,fwhich patent is hereby made a part of this application as if fully set forth herein.

The circuits at station A operate in substantially the same manner during'the reception of Signals over `this system as described in the above-identified applications of Cramer and Cramer et al. z

At the repeater or switching point B., the transmission conductor 24 is connected to a circuit which extends `through the lower winding of relay 3|) to ground through the marking contacts of relay 32. Hence relay 30 follows the signals transmitted by the transmitting device Relay 30` is provided with a network comprising resistance 4 2 and condenser 43 for altering the bias current owing through the upper winding vof this relay during the reception of signals so that Athis bias current varies in such a manner rastocompensatelor Variations in the received 'current due to the particular characteristics of each of the code combinations received over the line.,` AThe operation of networks of this type has been described in `greater-detail in the co-pendingv application of Kinkead filed on the same day as this application.

Relay 3U follows the signals received over conductor or line 2 4 and repeats them to the upper winding of relay 3| and causes this relay in turn to repeat the signals through the switching unit 5U to the other repeater shown to the left in the drawing. At this time transmitting relay 32 remains in the position shown in the drawing, hence vno current flows through the lower winding of relay 3`| at this time. It should be noted that relay `:il in eiect receives polar signals because the up- ,while the other terminal of this winding is connected to thel armature of the receiving relay 3 0. .The armature of this relay moves alternately betial.

tween ground and the full'f` battery.- potential.l`4` Hence the current flowing through'the upper winding of relay 31 is reversed under control of l relay 30 in accordance with the received signals.

When signals are received through switching unit U, they will flow through the lower winding of relay32 and be repeated by this relay through the lowerwinding of relay to` the transmission conductor 24 and thence to station A."

Due to the surge currents causing the capacity 25 of` line 24` to be alternately discharged and charged during the operation'of relay 32, it has been found practically impossible to prevent the armature of relay 3i) from responding for short intervals of time to the surgetcurrents.`

Iniorder to preventV relay 3Fl from also following these short momentary operations of the armature of relay 30, a path is completed ,through the lower winding of relay 3i at this time from` battery `through the spacing contact and arma-` ture of relay 32, resistance 35, rectifierlBJ-landresistance` 36 to ground through the lower winding of relay 3l. Condenser `34 is also connected from rectifier 33` to ground. Hence the upper terminal i of condenser 34 is charged to a positive poten- Whenrelay 32 moves-to its marking position, the above-traced circuits from the `lower winding of relay 3l are interrupted` However,

the upper terminal of condenser 34 immediately starts discharging through this winding and tends to maintain the armature of relay 3l in its mark` ing position and thus prevents this relay from following the momentary operation of the arma-` ture of relay 3l). Thus at this end of the system, the` repeating relay 3|. is prevented from following momentary improperoperation of the receiv` ing relay 3E) during the time signals are transmitted from this station.` i

Condenser is connectedbetween the main` line winding and the biasing winding of relay 30. and serves to improve` the operation :of` relay by causing charging and discharging currents tothis the directions of the twoV currents arefreversed, while their Imagnitudes `remain substantially` the` same. This `means that the net effect upon'the.

armature of relay 2 Il is Anowreversed so that this i relay will operateto its spacingposition andthus repeat the spacing pulses to selector magnet lill. I to provide a copy atstation A of message signals...

transmitted therefrom.

During thetransmission of signalsfrom sta` tion A, the` line c'apacityZE.` is charged and: dis-f charged through the upperwindingof relay 2|.

As pointed` out above, the currents flowing through this `winding are opposed to. the currents which actually controlthe` operation` of the; armature off thisrelay and since the charging currents maybe of considerable magnitude, they may' interfere with the proper operation. of.. the` relay;

vIn. order to .reduce the. effects of. these charging this manner the charging surges of both pclarities are prevented from seriously interfering `the operation of relay 2l at this time.

These pulses of positive and negative. currents are transmitted over `line 24 through the-.lower winding of relay 3D to ground through the armature and marking Contact of` relay 32. Itheapplicationof these substantially equal positiveand `affected in the same manner, i. e. their magnicondenser to flow through the biasing winding thus tendingto reduce the tendency of relay to `peres flows in line 24 due to the negative potential applied to the `line by relays I3 `and `Hl from rectifier i2. Further,` consider the; transmission l of signals from station `1A tostation B. During spacing pulses the positions of the armatures `of r relays i3 and I4 will be reversed and cause a positive potential from rectierfi2 tobe applied to line 24. This positive potential. is equal in magnitude to the negative potential applied to the` line during marking pulses.

As set forth in thelabove-identined Cramer applications, a biasing current flows through the lower winding of relay 2| which produces an effect upon the armature of this relay which is substantially twice the effect of the current flowing through the line winding. Assume that this cur-` rent is sixty milliamperes and that the windings of the relay 2| are substantially the same. If current flowing through the lower winding of this relay at this time tends to hold the armature of this relay in its marking position and current flowing through'the upperwinding tends to op crate the armature to spacing position,` the net effect upon the armature will be equivalent to thirty milliamperes `tending to holdfthaarmature of relay 2l inits marking position; t

When spacing potential"`is"`appli`ed to `line 24,

`negative potentials to the line at station A will;`

therefore, vcause. substantially equal 1 currents to flow over line.24 and throughthe lower winding of relay, ,u,Underthesecircumstances, aspoint-` ed out -in` the above-identified Cramer applica-` .i

tions, variations in the leakage resistance; offline 24wi11 not add to or subtract from the distortion of the signals transmitted over the line; Invother` words, boththe positive: and negative pulses are tudes arevaried1 in like` manners and to substantially `the same extent by variation in leakage resistance of the line and hence relay 3Ilrwillr re- ,i 1 spondf toboth of these types` of pulsesequally i well.I `lllnder these circumstances no `additional i distortion or bias is added to or taken; away from any of` the `signals transmitted over the line; 24 due to variations` in the leakageresistance 264 of this line. i

The receiving relay usually employedto respond to signals of this type, such `asdescribed:A inthe above-identified patents to Cramen; is `generally not provided with any electricalor `mechanical bias because the relayiusually receives pulseshof` positive and negative current which are `ofzsubzstantially `equal magnitude for` operating` its `armature to either one or theother of its positions.

When a receiving relay is Operated` over such high capacity lines sothat the pulses do notreach their steady state value within a single pulse interval, theresponseof the relay is in partdetermined by the length of the previous` pulse, `asf-.set forth in the above-identified copending` application of Kinkead. l In order to compensate.` for the effects of the high line capacity, condenser ll3fand resistancenetwork 42 are connected to the` upper or biasing winding of` `relay 30 `and so arranged that current flowing through the upper winding of this relay-is controlled by received signals and is` in such a direction aslto counteract the effects of lhigh linecapacity.` For example, duringthe application of` longo marking pulses; ,towlinei 24 at ,station` A, the line currentA throughf the 1 lower winding of relay will reach its maximum value. Under these conditions, a positive potential from the marking contact of relay 30 and its armature is applied to the upper terminal of condenser 43 and causes ay current to ilow through the upper winding of this relay Which tends to oppose the curent flowing through the lower winding of this relay. During the application of the long spacing pulse of line 24, current through the lower winding of this relay will fall substantially to zero at which time the armature of the relay will apply ground potential to the upper terminal of condenser 43 and cause a reverse current to now through the upper winding of relay 3l). This reverse current tends to cause the relay to operate more readily to its marking position. Thus after long pulses of either polarity are applied to line '24, a biasing current flows through the upper winding of relay 30 which tends to aid the operation of relay 30 to the opposite position. By f arranging the constants of condenser 43, the resistance 42 together with' resistances 39 and 4t and the upper winding of relay 30 so that the currents reach their steady state value at substantially the same time as the line current reaches its steady state value, the response of relay 30 is substantially independent of the length of the pulse preceding the pulse to which the relay must respond. Hence, this type of distortion normally encountered due to high line capacity is materially reduced if not altogether eliminated.

Relay 30 in responding to the signals transmitted from station A repeats them to the upper winding of relay 3| by rst connecting positive battery and then ground to the lower terminal of the upper winding of this relay. The upper terminal of the upper winding of relay 3| is connected to the mid-point of a potentiometer comprising resistances 3l, 38 and 4|. Consequently, current. owing through the upper winding of relay 3| is in one direction when the armature of relay 30 is in contact with positive potential connecting to its marking contact, and is in the opposite direction when armature of relay 3|) is in its A, spacing position where it is resting against ground connected to the spacing contact. Since relay 32 is in its marking position and has ground connected to its armature at this time, no current flows through the lower winding of relay 3 l. Relay 3I, therefore, accurately follows ythe signals transmitted from station A and repeats them through the switching equipment 50.

Relay 3| in repeating signals to the switching equipment 50 connects ground to the circuit extending through its armature during spacing pulses and positive battery through the lower winding of relay 32 during marking pulses. Similarly, when signals are transmitted from switching equipment 50 tostation A, they will be transmitted through the armature and marking ontact of relay 3| to positiveA battery through the lower winding of relay 32. These signals will comprise ground spacing pulses and positive battery for marking pulses.

During transmission of signals from the switching equipment 5i! to line 24, relay 3| is normally maintained in its marking position and consequently these pulses will be transmitted through the lower winding of relay 32.

Relay 32 will respond to these signals and repeat them over line 24 by connecting positive potential to line 24 in response to the spacing pulses and ground potential in response to the marking pulses. Upon application of positive potential to line 24, a surge of charging current ows through the lower winding of relay 30 and tends to maintain this relay in its marking position. Upon the application of ground potential to the line 24, the surge of discharge current from the line capacity 25 also flows through the lower winding of relay 30. In this case, however, the surge is in the reverse direction and tends to operate relay 33 to its spacing position for a short interval of time. It is generally undesirable to permit the receiving relay to so respond and it is frequently necessary to adjust the relay so that it is relatively insensitive to these surges. This means that the relay is also relatively insensitive to signals received over line 24. Consequently, the length of line over which the satisfactory signals willbe transmitted is greatly reduced.

In accordance with the present invention, relay 30 is adjusted so that it will respond to weak signals from line 24. This means that the armature may leave its marking contacts under the circumstances described above. However, relay 3l is prevented from following the short im- -proper operation of relay 30 at this timel due to the fact that during the time spacing potential is applied to line 24, positive potential through rectifier 33 is connected to the upper termina1 of condenser 34 and current also flows through the armature and marking Contact of relay,32 so this condenser starts to discharge through this lower winding of relay 3| and the effect of the discharge current is sufficient to prevent relay 3i from following the short improper operations of the armature of relay 30 at this time. v

As pointed out above, the lower winding of relay 3| produces no effect upon `this relay duringr the transmission of signals in the reverse direction so that it does not introduce any distortion or interfere with signals transmitted in the reverse direction, but does prevent improperoperation of this relay during transmission from the switching unit 53. By thus preventing improper operation of this relay, the circuit through the lower winding of relay 32 is maintained closed and the transmission of signals from switching equipment 50 through repeater 32 to line 24 is not interfered with and at the same time relay 3D may be a sensitive relay which will respond to weak signals received over a long line.y

In the specific embodiment of this invention described herein, the potential connected to the spacing contact of relay 32 is approximately twice the magnitude of the potential developed by rectifier I2 and is of opposite polarity to the potential connected to line 24 by relays I3 and I4 during the transmission of marking condition by them to line 24. Consequently, the line current under these circumstances rises to a value of approximately three times the normal marking current flowing through line 24. t

Under the conditions assumed above, where the normal line current is thirty milliamperes flowing in a negative direction, the line current will rise to ninety'milliamperes also flowing in a negative direction in response to the transmission of a spacing pulse by relay 32.

The spacing pulse transmitted over linev 24 to ing said bias.

tortion'to received signals,V receiving apparatus connected to each end of said line, means for applying an electrical bias to one of said receiving apparatus, and' apparatus automatically controlled solely by said receiving apparatus for Vary- 3.An impulse transmitting system comprising a line, impulse receiving apparatus connected to each end of said line, impulse transmitting apparatus connected' to eachend of said line for transmitting -tvfodifferentV impulse currents over said line, means for so' establishing the polarities and vmagnitudes of said currents with respect to each other and to the electrical characteristics ot said line that the bias of said impulses as received at the opposite end of the line is substantially constant and independent of the leakage resistance of said line, repeating apparatus at one end of said lline actuated by said impulse receiving apparatus, and'means controlled by the transmitting apparatus at said one end for preventing the uoperation of said repeating apparatus during the operation of said transmitting apparatus.

4. Anv impulse transmitting system comprising 'a telegraph transmission line, impulse receiving apparatus connected to each end of said line,

impulse transmitting apparatus connected to yeach end of said line for transmitting two difi ferent impulse currents over said line, means for so establishing the polarities and magnitudes of said'currents with respect to each other and to the electrical characteristics of said line that the bias of said impulses as received at the opposite end of the line is substantially constant and independent of the leakage resistance of said line, repeating apparatus at one end of said line actuated by said impulse receiving apparatus, means controlled by the transmitting apparatus at said one end for preventing the operation of said repeating apparatus during the operation of said transmitting apparatus, bias means for the receiving apparatus at the other end of said line, and means controlled by the transmitting apparatus at said other end for reversing said bias.

5. In a telegraph system, a telegraph transmission line havingv electrostatic capacity and subject to leakage resistance, transmitting apparatus `connected to the ends of said line for applying signaling potentials thereto which are so related to each other and to said line that variations of said leakage resistance do not add distortion to 4received signals, receiving apparatus connected to each end of said line, means for applying an electrical bias to one of said.

receiving apparatus, and means controlled solely by said one receiving apparatus for varying the bias applied thereto to reduce distortionv of signals received by said receiving apparatus due to said electrostatic capacity.

RITA SMITH KINKEAD, Administratria; of the Estate of Fullerton S.

Kz'nlcead, Deceased. 

